Information recording medium and reproduction device

ABSTRACT

An optical disk ( 100 ) of the present invention includes (i) a medium information region ( 101 ) (a) in which type identification information is recorded by recesses and/or protrusions which are formed by a given modulation method and whose lengths are longer than a length of an optical system resolution limit of a playback device and (b) in which first address information is recorded in a first address data format and (ii) a data region ( 102 ) (a) in which content data is recorded by recesses and/or protrusions which are formed by the given modulation method and which include a recess and/or a protrusion whose length is shorter than the length of the optical system resolution limit and (b) in which second address information is recorded in a second address data format.

TECHNICAL FIELD

The present invention relates to (i) an information recording medium inwhich information can be recorded and (ii) a playback device capable ofplaying back the information recording medium.

BACKGROUND ART

In order to store large amounts of data such as a high image qualityvideo, there has recently been a demand for a large-capacity informationrecording medium. A high-density information recording medium that isexpected to satisfy such a demand is exemplified by a super-resolutionmedium (i) in which content information is recorded by a pit groupincluding a pit that is shorter in length than an optical systemresolution limit and (ii) which is played back by higher playback powerthan normal.

In order to ensure compatibility between information recording mediums,an information recording medium is generally provided with not only adata region (i.e., a region in which content is recorded) but also amedium information region (i.e., a region in which information foridentifying a type of an information recording medium is recorded). Byplaying back the medium information region, a playback device readsinformation that is necessary for playing back the data region.Subsequently, the playback device plays back the data region.

As in the case of a normal medium (i.e., a non-super-resolution medium),a super-resolution medium is also provided with a medium informationregion and a data region that are identical in recording density.Against a background of this, there have been proposed various methodsfor responding to an increase in total number of clusters due to anincrease in recording density.

Patent Literature 1 discloses a method for recording address informationin each of a medium information region and a data region of asuper-resolution medium by use of an address data format which differsfrom that of a normal medium. (b) of FIG. 15 illustrates an address dataformat of a super-resolution medium disclosed in Patent Literature 1.(a) of FIG. 15 illustrates an address data format of a normal mediumdisclosed in Patent Literature 1.

CITATION LIST Patent Literature

[Patent Literature 1]

Japanese Patent Application Publication Tokukai No. 2010-262713(Publication date: Nov. 18, 2010)

SUMMARY OF INVENTION Technical Problem

However, playback of an information recording medium via a conventionalplayback device capable of playing back both a super-resolution mediumand a normal medium (i.e., a playback device having downward playbackcompatibility) causes the following problems.

Specifically, assume that an address data format which differs from thatof a normal medium (i.e., an address data format for a super-resolutionmedium) is applied to not only the data region but also the mediuminformation region of the super-resolution medium as in the methoddisclosed in Patent Literature 1. In this case, since a type of a mediumis unknown when the medium information region of an informationrecording medium starts to be played back via a playback device, it isnecessary to assume a case where the information recording medium to beplayed back is a normal medium that is inadaptable to higher playbackpower for playing back a super-resolution medium. This requires theplayback device to start playing back the information recording mediumby use of a normal medium playback setting (i.e., lower playback power,a normal medium error correction method, etc.).

FIG. 16 is a flowchart showing an example of how a conventional playbackdevice plays back an information recording medium. After a normal mediumplayback setting has been selected (process S101), a playback deviceattempts to playback a medium information region (process S102). Then,in a case where the medium information region is improperly played back(“NO” at S102), the playback device determines that the informationrecording medium to be played back is a super-resolution medium, selectsa super-resolution medium playback setting (process S104), and playsback a data region (process S105). Meanwhile, in a case where the mediuminformation region is properly played back (“YES” at S102), the playbackdevice determines that the information recording medium to be playedback is a normal medium, and plays back the data region without changingthe normal medium playback setting (process S103).

However, according to the process shown in FIG. 16, even in a case wherea normal medium having a medium information region that cannot be playedback properly due to some reason such as dirt on that medium is loadedin a playback device, the playback device also determines that thenormal medium is a super-resolution medium.

This is because according to a conventional playback device, aninability to play back the medium information region is a criterion fordetermining that the information recording medium is a super-resolutionmedium.

Thus, it is expected that, despite the fact that the informationrecording medium to be played back is a normal medium, asuper-resolution medium playback setting will be applied to the normalmedium and a medium information region of the normal medium will beirradiated with playback light having higher playback power for playingback a super-resolution medium.

However, a normal medium, which has no durability to withstand playbacklight having higher playback power for playing back a super-resolutionmedium, may be broken when irradiated with such playback light.

Thus, due to some reason such as adhesion of dirt to the informationrecording medium, the playback device loses its downward compatibility.This causes a problem of a fear of breakage by mistake of a normalmedium that essentially has no problem.

The present invention has been made so as to solve the above problems,and an object of the present invention is to provide an informationrecording medium suitable for a playback device to carry out playbackwith higher reliability.

Solution to Problem

In order to attain the above object, the information recording mediumaccording to an aspect of the present invention is an informationrecording medium including: a first region in which type identificationinformation for identifying a type of the information recording mediumis recorded by recesses and/or protrusions which are formed by a givenmodulation method and whose lengths are longer than a length of anoptical system resolution limit of a playback device; and a secondregion in which content data is recorded by recesses and/or protrusionswhich are formed by the given modulation method and which include arecess and/or a protrusion whose length is shorter than the length ofthe optical system resolution limit, the first region containing firstaddress information recorded therein in a first address data format, andthe second region containing second address information recorded thereinin a second address data format that differs from the first address dataformat.

Advantageous Effects of Invention

The information recording medium according to an aspect of the presentinvention yields an effect of providing an information recording mediumsuitable for a playback device to carry out playback with higherreliability

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a set of views (a) and (b). (a) of FIG. 1 is a plan viewshowing an example of a configuration of an optical disk according toEmbodiment 1 of the present invention, and (b) of FIG. 1 is across-sectional view showing an example of a configuration of recordinglayers of the optical disk.

FIG. 2 is an enlarged view of a boundary part between a mediuminformation region and a data region of the optical disk of Embodiment 1of the present invention.

FIG. 3 is a view schematically illustrating a cross section of theoptical disk of Embodiment 1 of the present invention.

FIG. 4 is a set of views (a) and (b). (a) of FIG. 4 is a view showing anexample of a structure of an address unit number used in the mediuminformation region of the optical disk of Embodiment 1 of the presentinvention, and (b) of FIG. 4 is a view showing an example of a structureof an address unit number used in the data region of the optical disk.

FIG. 5 is a set of views (a) and (b). (a) of FIG. 5 is a view showing anexample of a structure of an address unit group of the optical disk ofEmbodiment 1 of the present invention, and (b) of FIG. 5 is a viewshowing an example of a structure of an address unit “AU0”, which is oneof address units of the address unit group.

FIG. 6 is a view illustrating a structure of a main data block (cluster)of the optical disk of Embodiment 1 of the present invention, in whichmain data block main data is recorded, and an example of an arrangementof address units (address fields) in the main data block.

FIG. 7 is a block diagram illustrating a configuration of a playbackdevice of Embodiment 2 of the present invention.

FIG. 8 is a view illustrating a specific configuration of a decodingprocess section of Embodiment 2 of the present invention.

FIG. 9 is a flowchart showing an example of a flow of processes that theplayback device of Embodiment 2 of the present invention carries out toplay back an information recording medium.

FIG. 10 is a plan view showing an example of a configuration of anoptical disk of Embodiment 3 of the present invention.

FIG. 11 is an enlarged view of a boundary part among a mediuminformation region, a blank region, and a data region of the opticaldisk of Embodiment 3 of the present invention.

FIG. 12 is a plan view showing an example of a configuration of anoptical disk of Embodiment 4 of the present invention.

FIG. 13 is an enlarged view of a boundary part between a mediuminformation region and a data region of the optical disk of Embodiment 4of the present invention.

FIG. 14 is a plan view showing an example of a configuration of anoptical disk of Embodiment 5 of the present invention.

FIG. 15 is a set of views (a) and (b). (a) of FIG. 15 illustrates anaddress data format of a normal medium disclosed in Patent Literature 1.(b) of FIG. 15 illustrates an address data format of a super-resolutionmedium disclosed in Patent Literature 1.

FIG. 16 is a flowchart showing an example of how a conventional playbackdevice plays back an information recording medium.

DESCRIPTION OF EMBODIMENTS Embodiment 1

Embodiment 1 of the present invention will be described below withreference to FIGS. 1 through 7.

(Configuration of Optical Disk 100)

The following description discusses, with reference to FIG. 1, aconfiguration of an optical disk 100 (information recording medium). (a)of FIG. 1 is a plan view showing an example of a configuration of theoptical disk 100, and (b) of FIG. 1 is a cross-sectional view showing anexample of a configuration of recording layers of the optical disk 100.Note that Embodiment 1 discusses a case where the optical disk 100 is aread-only Blu-ray (registered trademark) Disc (BD).

The optical disk 100, which is a discoid super-resolution medium, has(i) a medium information region 101 (first region) in which informationon the optical disk 100 is recorded and (ii) a data region 102 (secondregion) in which content such as video or software is recorded.

In the medium information region 101 and the data region 102, (i)information on the optical disk 100 and (ii) content (content data),respectively, are recorded by a given modulation method (e.g., the 1-7PP (Parity Preserve/Prohibit RMTR (Repeated Minimum Translation RunLength)) modulation recording method) by marks and spaces constituted bypit groups.

Specifically, information on the optical disk 100 is recorded in themedium information region 101 in a form of pits of the mediuminformation region 101, and content is recorded in the data region 102in a form of pits of the data region 102.

For example, in the case of a BD, the 1-7 PP modulation recording methodis used, and thus information on the optical disk 100 and content arerecorded by marks and spaces of 2T through 8T.

The medium information region 101 is provided in an innermost part(so-called “lead-in region”) of the optical disk 100. In the mediuminformation region 101, pieces of information such as mediumidentification information (type identification information) andmanagement information for recorded data are recorded as information onthe optical disc 100 by a pit group made up only of pits longer than anoptical system resolution limit (described later) (0.119 μm). The mediuminformation region 101 is identical in recording density to a normalmedium.

The medium identification information is information for identifying atype of an information recording medium. The medium identificationinformation includes, for example, disk type identification informationsuch as a type of the optical disk 100 (BD, DVD, read-only, write-once,rewritable, etc.) and a storage capacity of the optical disk 100, andindividuality identification information for identifying each individualoptical disk 100. The management information is information indicativeof, for example, an address at which a piece of information is recorded,and a relationship among a plurality of pieces of information.

The data region 102 is provided in the optical disk 100 so as to beouter than the medium information region 101. In the data region 102,content (i.e., information to be used by a user) is recorded by the 1-7PP modulation recording method by a pit group including a pit that isshorter than the optical system resolution limit. Thus, the data region102 is higher in recording density than the medium information region101.

Assuming that a wavelength of playback light of a playback device suitedto the optical disk 100 is λ and a numerical aperture is NA, an opticalsystem resolution limit of the playback device is expressed as λ/(4×NA).According to the optical disk 100, the optical system resolution limitis expressed as λ/(4×NA)=0.119 μm where λ=405 (nm) and NA=0.85.

FIG. 2 is an enlarged view of a boundary part between the mediuminformation region 101 and the data region 102 of the optical disk 100.According to the optical disk 100, in which various pieces ofinformation are recorded by the 1-7 PP modulation recording method, themedium information region 101 has a minimum pit length, which is a 2Tpit length (i.e., R2T), of 0.149 μm, and the data region 102 has aminimum pit length, which is a 2T pit length (i.e., D2T), of 0.112 μm.

Note that a “pit length” means a length of a pit that is formed of arecess and/or protrusion, and generally means a length in acircumferential direction of the optical disk 100.

Further, a track pitch of a track formed by a pit group in the mediuminformation region 101 and a track pitch of a track formed by a pitgroup in the data region 102 are equal to each other (e.g., 0.35 μm).Note that a track pitch is a distance between two adjacent tracks in aradial direction of the optical disk 100.

FIG. 3 is a view schematically illustrating a cross section of theoptical disk 100. The optical disk 100 includes a cover layer 191, afunctional layer 192, and a substrate 193 that are provided in thisorder from a side on which playback light supplied from a playbackdevice is incident.

The cover layer 191 is made of, for example, an ultraviolet curableresin having a thickness of 100 μm. The cover layer 191 which is made ofsuch an ultraviolet curable resin has a refractive index ofapproximately 1.5 with respect to playback light having a wavelengthλ=405 nm.

Note that the cover layer 191 can be made of any material that has ahigh transmissivity with respect to a wavelength λ of playback light.Thus, a material of which the cover layer 191 can be made is exemplifiedby, but not particularly limited to, a combination of a polycarbonate(PC) film and a transparent adhesive.

The substrate 193 is made of, for example, polycarbonate having adiameter of 120 mm and a thickness of 1.1 mm. On the substrate 193,information is recorded by pits which are constituted by recesses and/orprotrusions provided on a surface of the substrate 193 which surface islocated on a side on which playback light is incident.

Note that the substrate 193 can be made of any material that has asurface on which information can be recorded by pits constituted byrecess and/or protrusions and which is located on a side on whichplayback light is incident. Thus, the substrate 193 can be made of, forexample, polycarbonate resin and acrylic resin (PMMA), polyester,alicyclic hydrocarbon resin, epoxy acetal synthetic resin, or glass. Amaterial of which the substrate 193 is made is not particularly limited,provided that the material can meet standards of a strength and aflatness that are required of a substrate.

The functional layer 192 is made of, for example, Ta having a thicknessof 12 nm. The functional layer 192 is a film that allows a playbackoptical system to read information recorded by a prepit group providedon a surface of the substrate 193. Note that the “prepit group” means aplurality of irregularities provided on the substrate 193.

That is, the functional layer 192 can be any super-resolution film whichallows a playback optical system to carry out playback (i.e.,super-resolution playback) even in a case where an average of lengths ofa minimum pit and a minimum space, which are provided in the pit group,is smaller than the optical resolution limit. The functional layer 192can be formed by, for example, sputtering.

The functional layer 192 can be made of, for example, a material such asSi, Ge, GeSbTe, AgInSbTe, Al, Ag, Au, or Pt, or a mixture of thesematerials (e.g., APC).

Furthermore, the functional layer 192 can be made of a stack of two ormore types of films. The functional layer 192 can be made of, forexample, a stack of (i) a light absorption film having a thickness of 8nm and made of a material such as Ta, Al, Ag, Au, or Pt, or a mixture ofthese materials and (ii) a super-resolution playback film made of amaterial such as ZnO, CeO₂, or TiO₂. The functional layer 192 which ismade of the light absorption film and the super-resolution playback filmallows playback of information also in a case where the optical disk 100has a higher recording density.

Further, the functional layer 192 can include two or more layers. Thefunctional layer 192 which includes two or more layers only needs to beprovided with an intermediate layer located between respectivefunctional layers of the functional layer 192.

The intermediate layer can be made of, for example, an ultravioletcurable resin. The intermediate layer can be made of any material (i)that has a high transmissivity with respect to a wavelength λ ofplayback light and (ii) that has a surface on which content can berecorded by pits constituted by recesses and/or protrusions and which islocated on a side on which playback light is incident.

Note that, in a case where the functional layer 192 includes two or morelayers, the medium information region 101 needs to be provided in aninner part of at least one of the functional layers of the functionallayer 192. This allows the data region 102 to be larger, and enables theoptical disk 100 to have a greater capacity.

The medium information region 101 does not necessarily need to beprovided in the innermost part of the optical disk 100. Alternatively,the medium information region 101 can be provided in an outer part(so-called “lead-out region”) of the optical disk 100.

(Configuration of Address Data)

According to Embodiment 1, embossed pits (i.e., recesses and/orprotrusions) formed on the substrate 193 cause address information(address data) to be recorded in each of the medium information region101 and the data region 102. Specifically, address information isrecorded in each of the medium information region 101 and the dataregion 102 by the modulation method (described earlier) by marks andspaces constituted by pit groups.

The following description discusses, with reference to FIGS. 4 through6, (i) an example of structures of address unit numbers (AUN) (AUNstructures) of each of the medium information region 101 and the dataregion 102, in each of which address information is stored, and (ii) anexample of a structure of an address unit (AU) including the addressunit numbers.

First, the example of the structures of the address unit numbers (AUN)is described below with reference to FIG. 4. FIG. 4 is a set of viewswhich set shows the example of the structures of the address unitnumbers. (a) of FIG. 4 is a view showing an example of a structure of anaddress unit number 111 used in the medium information region 101 of theoptical disk 100, and (b) of FIG. 4 is a view showing an example of astructure of an address unit number 121 used in the data region 102 ofthe optical disk 100. Note that among the address unit numbers, “AUN0”is the least significant symbol and “AUN3” is the most significantsymbol.

As with the address unit numbers, among types of parity, which aredescribed later and are illustrated in (b) of FIG. 5, “Parity0” is theleast significant symbol, and “Parity3” is the most significant symbol.

As illustrated in (a) of FIG. 4, the medium information region 101 isprovided with “AUN0” through “AUN3” as an address unit number 111 having4 symbols (1 symbol=8 bits). That is, “AUN0” through “AUN3” are eachconstituted by 1 symbol (8 bits), and these 4 symbols are indicated bybits A0 through A31. The bits A0 through A31 which constitute theaddress unit number 111 function as below.

Bits A0 through A4 (5 bits) are each an in-cluster number. A cluster isa unit of data recording. In the case of a recordable disk, the clusteris a unit constituting 1 RUB (recording unit block: recording playbackcluster).

Bits A5 through A23 (19 bits) are each a cluster address.

Bits A24 through A26 (3 bits) are each a layer number (recording layernumber).

Bits A27 through A31 (5 bits) are reserve bits.

The address unit number 111 employed in the medium information region101 is identical to that employed in a normal medium (i.e., anon-super-resolution medium).

As illustrated in (b) of FIG. 4, the address unit number 121 of the dataregion 102 also has 4 symbols which constitute respective “AUN0” though“AUN3” indicated by bits A0 through A31. The bits A0 through A31 whichconstitute the address unit number 121 function as below.

Bits A0 through A3 (4 bits) are reserve bits.

Bits A4 through A8 (5 bits) are each an in-cluster number.

Bits A9 through A28 (20 bits) are each a cluster address.

Bits A29 through A31 (3 bits) are each a layer number.

Since the data region 102 has a high recording density than a normalmedium, the cluster addresses (i.e., bits A5 through A23 (19 bits)) ofthe address unit number 111 used in the medium information region 101can be said to be insufficient to express the cluster addresses (i.e.,bits A9 through A28 (20 bits)) of the address unit number 121 used inthe data region 102.

Thus, according to the data region 102, assuming that the bits A9through A28 (20 bits) are the cluster addresses of the address unitnumber 121, the cluster addresses of the address unit number 121 areincreased by 1 bit as compared with those of the address unit number 111of the medium information region 101 (see (b) of FIG. 4). This solvesthe problem of insufficiency of cluster addresses in the data region102.

Note that the address unit number 121, whose structure is not limited tothe structure described above, only needs to have any structure in whichthe cluster addresses of the address unit number 121 are greater innumber of bits than those of the address unit number 111.

As described earlier, the address unit number 111 used in the mediuminformation region 101 (first address data format (address method)) hasa data structure which is identical to a data structure of an addressunit number used in an information recording medium (i.e., a normalmedium) constituted by recesses and/or protrusions whose lengths arelonger than that of the optical system resolution limit of a playbackdevice.

Meanwhile, the address unit number 121 used in the data region 102(second address data format) has a data structure which differs from adata structure of the address unit number 111 used in the mediuminformation region 101 and which further enables recording of denserdata than a normal medium.

Thus, in the medium information region 101, address information isrecorded in the first address data format, which is identical to that ofa normal medium. Meanwhile, in the data region 102, address informationis recorded in the second address data format, which differs from thefirst address data format and which further enables recording of denserdata than a normal medium (e.g., a data structure in which the clusteraddresses are greater in number of bits (number of addresses) than thoseof a normal medium).

In other words, since pieces of information are recorded in the addressunit number 111 and the address unit number 121 in respective differentaddress data formats, the address unit number 111 and the address unitnumber 121 differ in structure.

Here, an error correction code (ECC) encoding process is carried outwith respect to each of the address unit number 111 and the address unitnumber 121 in address units illustrated in FIG. 5. (a) of FIG. 5 is aview showing an example of a structure of an address unit group, and (b)of FIG. 5 is a view showing an example of a structure of an address unit“AU0”, which is one of address units of the address unit group. Notethat a method that can be used to carry out the ECC encoding withrespect to main data is either one of a long distance code (LDC) methodand a burst indicator subcode (BIS) method.

(a) of FIG. 5 shows, as the example of the structure of the address unitgroup, a case where 16 address units of “AU0” through “AU15” areprovided. In this case, the address units “AU0” through “AU15” areconfigured as below.

Address unit “AU0” is constituted by 9 bytes of address fields “AF0,0”through “AF8,0”. That is, 1 address field is composed of 1 byte (1symbol).

Address unit “AU1” is constituted by 9 bytes of address fields “AF0,1”through “AF8,1”.

Similarly, the address units “AU2” through “AU15” are each constitutedby 9 bytes. That is, the Nth “AU(N)” is constituted by 9 bytes of“AF0,N” through “AF8,N”.

The ECC encoding is carried out with respect to these address units eachhaving 9 bytes (i.e., for each of “AU0” through “AU15”). The addressunits used in the medium information region 101 each include the addressunit number 111, a flag bit, and the types of parity. Similarly, theaddress units used in the data region 102 each include the address unitnumber 121, the flag bit, and the types of parity.

Specifically, an address unit is a data group that is provided so as toinclude at least (i) address information indicative of an address ofdata (recorded data) recorded on the optical disk 100 or an address ofdata (playback data) to be read out from the optical disk 100, and (ii)identification data that enables given encoding or decoding of theaddress information for error correction in a playback device suited tothe optical disk 100.

The address unit numbers each serve as the address information(described earlier). That is, each of the address unit numbers is dataindicative of an address assigned to recorded data or playback data. Thetypes of parity include the identification data (described earlier).That is, the types of parity include data that enables error correctionto the address units. The flag bit includes data indicative of a statein which recorded data is recorded. That is, the flag bit recordstherein, for example, information indicative of a state in whichrecorded data is recorded. Note that the flag bit can be used as areserve region in a read-only disk.

(b) of FIG. 5 illustrates the address unit “AU0”.

Address unit numbers of “AUN3”, “AUN2”, “AUN1”, and “AUN0” are assignedto respective address fields “AF0,0”, “AF1,0”, “AF2,0”, and “AF3,0” ofthe address unit “AU0”.

The flag bit is assigned to an address field “AF4,0”.

The types of parity (Parity3 through Parity0) are assigned to respectiveaddress fields “AF5,0” through “AF8,0”.

The address units “AU1” through “AU15” are each identical in structureto the address unit “AU0.” Thus, in the Nth address unit “AU(N)”,

address unit numbers “AUN3” through “AUN0” of “AU(N)” are assigned torespective address fields “AF0,N” through “AF3,N”,

the flag bit is assigned to an address field “AF4,N”, and

the types of parity (Parity3 through Parity0) are assigned to respectiveaddress fields “AF5,N” through “AF8,N”.

The error correction carried out by the ECC encoding for each of theaddress units is arranged such that, in a case where 9 symbols of eachof the address units include 4 symbols that are assigned to respectivetypes of parity, errors that occur within 2 symbols of the 9 symbols canbe corrected.

Thus, error correction encoding data to be formed as an address unit isa Reed-Solomon (RS) code having RS (9, 5, 5), a code length 9, data 5,and a distance 5.

In other words, the medium information region 101 of the optical disk100 has address units that include the address unit number 111 whose (9,5, 5) RS code has been subjected to an error correction encodingprocess. The data region 102 of the optical disk 100 has address unitsthat include the address unit number 121 whose (9, 5, 5) RS code hasbeen subjected to the error correction encoding process.

FIG. 6 is a view illustrating a structure of a main data block (cluster)in which main data is recorded and an example of an arrangement ofaddress units (address fields) in the main data block. Note thatinformation which is recorded, on tracks provided on each recordinglayer, by a phase change mark, a pigmentary change mark, or an embossedpit row is referred to as “main data (user data)”.

As illustrated in FIG. 6, a single main data block is composed of 496frames. That is, a single cluster is composed of 496 frames. Thoseframes each have a 155-byte structure in which data (38 bytes), BIS (1byte), data (38 bytes), BIS (1 byte), data (38 bytes), BIS (1 byte), anddata (38 bytes) are arranged.

That is, a single frame is composed of 152 bytes (=38 bytes×4) of dataand 3 bytes (=1 byte×3) of BIS, each of which is provided every 38 bytesof data. In this main data block having 496 frames, the address units“AU0 (Address Unit0)” through “AU15 (Address Unit15)” are arranged inrespective 31-frame units.

Specifically, 3 address fields are assigned to respective first 3 framesof each 31-frame group, which first 3 frames constitute BIS, so that theaddress units “AU0” through “AU15”, each of which is composed of 9 bytes(9 symbols), are arranged in the main data block. Thus, as illustratedin FIG. 6, the address units are arranged as below.

The address fields “AF0,0” through “AF8,0”, each of which has 1 byte(which have 9 bytes in total) and which constitute the address unit“AU0”, are arranged in the first 3 frames (which constitute BIS) of thefirst 31-frame group of the main data block.

The address fields “AF0,1” through “AF8,1”, which constitute the addressunit “AU1”, are arranged in the first 3 frames (which constitute BIS) ofthe second 31-frame group of the main data block.

Similarly, the address units “AU2” through “AU15” are arranged in therespective 3rd through 16th 31-frame groups.

As described earlier, the address units including the address unitnumber 111 are assigned to BIS of a main data block of the mediuminformation region 101, and the address units containing the addressunit number 121 are assigned to BIS of a main data block of the dataregion 102. That is, BIS includes the address information. In otherwords, BIS contributes to encoding of the address information.

(Effect of Optical Disk 100)

In a pit group of the medium information region 101 of the optical disk100, recesses and/or protrusions whose lengths are longer than that ofthe optical system resolution limit of a playback device (i.e., longerthan 0.119 μm) are formed by a given modulation method. In a pit groupof the data region 102, recesses and/or protrusions including a recessand/or a protrusion whose length is shorter than that of the opticalsystem resolution limit of a playback device are formed by the givenmodulation method.

Further, in the medium information region 101, address information isrecorded in the first address data format (i.e., an address data formatidentical to that of a normal medium), and in the data region 102,address information is recorded in a second address data format.

Thus, by irradiating the medium information region 101 with playbacklight having normal medium playback power, it is possible to read out(i) the address information and (ii) information on the optical disk 100(in particular, medium identification information) that are recorded inthe medium information region 101.

This allows a playback device to use successful playback of the mediuminformation region 101 as a criterion for determining that the opticaldisk 100 to be played back is a super-resolution medium. Especially in acase where the optical disk 100 is to be played back via a playbackdevice 1 of Embodiment 2 (described later), a region different from thedata region 102 of the optical disk 100 will not be irradiated withplayback light having super-resolution playback power.

That is, neither a normal medium nor the medium information region 101of the optical disk 100 will be irradiated with the playback lighthaving super-resolution playback power. Note that, since addressinformation is recorded in the data region 102 in the second addressdata format (described earlier), it is possible to read out, from thedata region 102, the address information and content by use of theplayback light having super-resolution medium playback power.

Thus, the optical disk 100 used as a super-resolution medium makes itpossible to prevent the playback device 1 of Embodiment 2 fromerroneously determining that a normal medium is a super-resolutionmedium. This makes it possible to prevent the occurrence of a situationin which a normal medium that is irradiated with playback light havinggreater playback power for playing back a super-resolution medium isbroken.

Thus, in a case where the optical disk 100 is to be played back by theplayback device 1 of Embodiment 2, it is possible to yield an effect ofenabling playback of an information recording medium with higherreliability. In other words, it is possible to provide the optical disk100 as a super-resolution medium that is suitable to be played back bythe playback device 1 of Embodiment 2.

In addition, the optical disk 100, in which the address data format ofthe data region 102 has been replaced with a format for a high densityinformation recording medium (i.e., the second address data format),also yields an effect of having a greater storage capacity withoutinsufficiency of addresses.

Embodiment 2

Embodiment 2 of the present invention will be described below withreference to FIGS. 7 through 9. Note that, for convenience, membershaving functions identical to those of the respective members describedin Embodiment 1 are given respective identical reference numerals, and adescription of those members is omitted in Embodiment 2.

(Configuration of Playback Device 1)

The following description discusses, with reference to FIG. 7, aconfiguration of a playback device 1 for playing back the optical disk100 of Embodiment 1. FIG. 7 is a block diagram illustrating theconfiguration of the playback device 1.

The playback device 1 is a playback device capable of playing back botha super-resolution medium and a normal medium. That is, it is possibleto apply, to the playback device 1, not only a playback setting forplaying back a super-resolution medium (i.e., a setting of playbacklight having higher power) but also a playback setting for playing backa normal medium (i.e., a setting of playback light having lower power).The following description refers to such a playback device as a playbackdevice having downward playback compatibility.

Note that, though Embodiment 2 discusses a case where the playbackdevice 1 is loaded with the optical disk 100 (i.e., a super-resolutionmedium), the playback device 1 can also be loaded with a normal medium.

The playback device 1 includes a spindle motor 2, an optical pickup 3, amotor 4 for the optical pickup 3, a detection circuit 5, a read circuit6, a decoding process section 7, an ECC decoding section 8, a controlsection 9, a servo circuit 10, a laser control circuit 11, a spindlecircuit 12, and a sensor 13. The playback device 1 is connected to anaudio visual (AV) system 20 that is externally provided.

By detecting that chucking of the optical disk 100 has been carried outwith respect to a turntable (not illustrated) of the playback device 1,the sensor 13 detects that the playback device 1 is loaded with theoptical disk 100. Then, the sensor 13 supplies, to the control section9, information indicating that the playback device 1 is loaded with theoptical disk 100.

The control section 9 which has obtained the information from the sensor13 instructs the spindle circuit 12 to rotate the spindle motor 2. Then,the control section 9 instructs the motor 4 to move the optical pickup 3to a given position. The motor 4 is a drive mechanism for moving theoptical pickup 3 to a given reading position. The control section 9 hasa function of collectively controlling operations of sections of theplayback device 1.

While moving in a radial direction of the optical disk 100 which isrotating, the optical pickup 3 irradiates the optical disk 100 withlaser light serving as playback light. The optical pickup 3 which hasreceived a drive signal (drive current) supplied from the laser controlcircuit 11 is driven to emit the laser light. Note here that theoperation of the laser control circuit 11 is controlled by the controlsection 9.

The playback device 1 plays back the optical disk 100 by use ofreflected light resulting from laser light reflected by the optical disk100. In order to play back the optical disk 100, the optical pickup 3includes a laser diode, an object lens, and a photodetector, which arenot illustrated.

The laser diode outputs laser light. The optical disk 100 is irradiatedwith the laser light via the object lens. Then, light reflected by theoptical disk 100 is detected by the photodetector.

The laser light outputted by the laser diode is, for example, laserlight having a wavelength of λ=405 nm. Further, the object lens has anumerical aperture of, for example, NA=0.85. Note that the wavelengthand the numerical aperture are not limited to these, and can be anywavelength and any numerical aperture each of which is specified inaccordance with a type or a class of the optical disk 100.

The reflected light detected by the photodetector of the optical pickup3 is supplied, in a form of a playback signal, to the detection circuit5. The detection circuit 5 generates not only the playback signal (i.e.,a radio frequency (RF) signal) but also a focus error signal and atracking error signal.

The detection circuit 5 supplies the focus error signal and the trackingerror signal to the servo circuit 10. The servo circuit 10 controls, inaccordance with the focus error signal and the tracking error signal,the operation of an actuator (not illustrated) of the optical pickup 3so that the laser light follows data tracking of the optical disk 100.

The detection circuit 5 also supplies the playback signal to the readcircuit 6. The read circuit 6 generates a playback clock from theplayback signal by use of a phase locked loop (PLL) (not illustrated).The read circuit 6 also carries out a demodulation process with respectto run length limited (RLL) (1, 7) modulation so as to demodulate theplayback signal.

The read circuit 6 supplies, to the decoding process section 7, aplayback clock signal and a result of the demodulation of the playbacksignal. The decoding process section 7 decodes an address by use of theresult of demodulation of the playback signal.

FIG. 8 is a view illustrating a specific configuration of the decodingprocess section 7. The decoding process section 7 includes a firstdecoding process circuit 71 a (first address information decodingprocess section), a second decoding process circuit 71 b (second addressinformation decoding section), and a switch 72.

The first decoding process circuit 71 a and the second decoding processcircuit 71 b are each connected to the read circuit 6. The switch 72 isconnected to each of the first decoding process circuit 71 a and thesecond decoding process circuit 71 b on its input side, and is connectedto the ECC decoding section 8 on its output side.

The first decoding process circuit 71 a has a function of decodingaddress information recorded in a first address data format. The seconddecoding process circuit 71 b has a function of decoding addressinformation recorded in a second address data format.

Thus, the first decoding process circuit 71 a can decode not onlyaddress information of a medium information region 101 but also addressinformation of a medium information region of a normal medium andaddress information of a data region. Further, the second decodingprocess circuit 71 b can decode address information of a data region102. The switch 72 has a function of selecting an output to the ECCdecoding section 8.

The read circuit 6 supplies, to each of the first and second decodingprocess circuits 71 a and 71 b of the decoding process section 7, theplayback clock signal and the result of demodulation of the playbacksignal. Then, the first decoding process circuit 71 a and the seconddecoding process circuit 71 b each decode a corresponding piece ofaddress information.

The address information obtained as a result of the decoding carried outby each of the first decoding process circuit 71 a and the seconddecoding process circuit 71 b is selected by the switch 72 in accordancewith which of the regions (i.e., the medium information region 101 andthe data region 102) of the optical disk 100 is to be played back by theplayback device 1, and then is supplied to the ECC decoding section 8.

That is, the switch 72 is switched so that (i) the first decodingprocess circuit 71 a which is carrying out its process is connected tothe ECC decoding section 8, and (ii) the second decoding process circuit71 b which is carrying out its process is connected to the ECC decodingsection 8. Note that the switch 72 causes a driver (not illustrated) ofthe decoding process section 7 to carry out the switching.

The ECC decoding section 8 carries out ECC decoding as a process forcorrecting an error. That is, the ECC decoding section 8 carries out theECC decoding with respect to the address information supplied from thedecoding process section 7, and generates a playback signal. Then, theECC decoding section 8 supplies the playback signal to the controlsection 9.

As described earlier, the address data format (first address dataformat) of the medium information region 101 has the structure (AUNstructure) of the address unit number 111 as illustrated in (a) of FIG.4. The address data format (second address data format) of the dataregion 102 has the structure (AUN structure) of the address unit number121 as illustrated in (b) of FIG. 4.

Thus, the ECC decoding section 8 carries out a decoding process that isin accordance with either of the address data formats. Thus, in a casewhere the ECC decoding section 8 incorrectly carries out this decodingprocess, the address information recorded in either of the address dataformats will not be properly decoded. That is, in such a case, it isimpossible to decode the address information.

Data included in the playback signal is decoded by the decoding processsection 7 and by the ECC decoding section 8, and then is supplied to theAV system 20 via the control section 9.

FIG. 7 shows, as an example, a configuration in which the playbackdevice 1 is connected to the AV system 20. Note, however, that an objectto which the playback device 1 is to be connected is not limited to theAV system 20. The playback device 1 can also be connected to, forexample, a personal computer.

Alternatively, the playback device 1 can be configured so as not to beconnected to another device. In such a case, the playback device 1includes, for example, an operation section and a display section, andan interface section for data input and output differs in configurationfrom that illustrated in FIG. 7. That is, the playback device 1 carriesout recording and playback in accordance with a user's operation, andincludes a terminal section for input and output of various data.

The spindle circuit 12 obtains, via the control section 9, the playbackclock signal generated by the read circuit 6. By comparing the playbackclock signal with a given rotation reference speed of the optical disk100, the spindle circuit 12 generates a spindle error signal and aspindle drive signal that is in accordance with the spindle errorsignal.

Further, by supplying the spindle drive signal to the spindle motor 2,the spindle circuit 12 controls an operation of the spindle motor 2 sothat the optical disk 100 is driven to rotate.

The spindle motor 2 can drive the optical disk 100 to rotate at aconstant linear velocity (CLV) or at a constant angular velocity (CAV).

(Process Flow of Playback Operation of Playback Device 1)

FIG. 9 is a flowchart showing an example of a flow of processes that theplayback device 1 carries out to play back an information recordingmedium (e.g., the optical disk 100). The following description discussesa case where an information recording medium to be played back is theoptical disk 100.

By detecting that chucking of the optical disk 100 has been carried outwith respect to a turntable (not illustrated) of the playback device 1,the sensor 13 detects that the playback device 1 is loaded with theoptical disk 100.

The control section 9 which has obtained from the sensor 13 theinformation indicating that the playback device 1 is loaded with theoptical disk 100 instructs the spindle circuit 12 to rotate the spindlemotor 2. Further, the control section 9 instructs the motor 4 to movethe optical pickup 3 to a given reading position.

Further, the control section 9 instructs the laser control circuit 11 tosupply a drive signal (drive current) to the optical pickup 3. Inaccordance with this drive signal, the optical pickup 3 irradiates themedium information region 101 of the optical disk 100 with laser lightserving as playback light and having normal medium playback laser power(e.g., low power of 0.35 mW). That is, a normal medium playback settingis set as a playback setting for playing back the medium informationregion 101 of the optical disk 100.

The optical pickup 3 which has received light reflected from the mediuminformation region 101 generates a playback signal (RF signal). Theplayback signal is supplied from the optical pickup 3 via the detectioncircuit 5 and the read circuit 6 to the decoding process section 7 andthe ECC decoding section 8. Processes S1 and S2 of FIG. 9 indicaterespective operations, carried out by the decoding process section 7 andthe ECC decoding section 8, for obtaining the address information of themedium information region 101.

The read circuit 6 (i) generates a playback clock from the playbacksignal by use of the PLL, and (ii) carries out a demodulation processwith respect to the RLL (1, 7) modulation so as to demodulate theplayback signal. The read circuit 6 supplies, to the decoding processsection 7, the playback clock signal and a result of the demodulation ofthe playback signal.

The above description has discussed the operations that the playbackdevice 1 carries out before carrying out the process S1 illustrated inFIG. 9. The following description will discuss processes S1 through S13with reference to FIG. 9.

The decoding process section 7 causes the first decoding process circuit71 a (i.e., a decoding process circuit for decoding the addressinformation recorded in the medium information region 101) to decode theaddress information read out from the medium information region 101(process S1) (first address information decoding process step).

The process S1 makes it possible to obtain pieces of address informationwhich pieces constitute the respective address units “AU0” through“AU15” illustrated in (a) of FIG. 4. That is, the process S1 makes itpossible to obtain, as the pieces of address information, AUN0 throughAUN3, flag data, and Parity0 through Parity3, which are 9 symbolsconstituting an address unit (AU).

The ECC decoding section 8 carries out, as a process for correctingerrors in the address information, the ECC decoding with respect to eachof the pieces of the address information obtained from the decodingprocess section 7 (process S2) (first ECC decoding step). The process S2makes it possible to obtain the address information whose errors arecorrected by the ECC decoding section 8.

In accordance with the address information obtained from the ECCdecoding section 8, the control section 9 controls an operation of themotor 4 so that the motor 4 moves the optical pickup 3 to a givenposition in the medium information region 101. Then, the optical pickup3 obtains medium identification information of the optical disk 100 froma given address of the medium information region 101 (process S3)(medium information obtaining step).

The control section 9 which refers to the medium identificationinformation of the optical disk 100 which information has been obtainedby the optical pickup 3 determines whether or not a type of aninformation recording medium loaded in the playback device 1 is asuper-resolution medium (process S4) (medium type determinationcondition). For example, in a case where the information recordingmedium loaded in the playback device 1 is the optical disk 100, thecontrol section 9 determines that the type of that information recordingmedium is a super-resolution medium.

The control section 9 which determines that the type of the informationrecording medium loaded in the playback device 1 is a super-resolutionmedium, (Yes at S4) selects, as a playback condition for playing backthe data region 102, a super-resolution medium playback setting (processS5) (playback setting selecting step).

The super-resolution medium playback setting differs from the normalmedium playback setting in, for example, playback power for playing backthe optical disk 100, and linear velocity at which the optical disk 100is driven to rotate. Note that the normal medium playback setting andthe super-resolution medium playback setting can be recorded in advancein a recording device (not illustrated) of the playback device 1.

Further, Embodiment 2 uses the normal medium playback setting as aninitial playback setting for the playback device 1. Thus, the normalmedium playback setting is selected during a period from startup of theplayback device 1 to the process S4.

The control section 9 controls an operation of the motor 4 so that themotor 4 moves the optical pickup 3 to a given position in the dataregion 102. Then, the optical pickup 3 irradiates the data region 102with the playback light. That is, the optical pickup 3 accesses the dataregion 102 (process S6) (data region accessing step).

The optical pickup 3 receives light reflected from the data region 102,and generates the playback signal (RF signal). The following processesS7 and S8 indicate operations, carried out by the decoding processsection 7 and the ECC decoding section 8, respectively, for obtainingaddress information recorded in the data region 102.

The read circuit 6 (i) generates a playback clock from the playbacksignal by use of the PLL, and (ii) carries out a demodulation processwith respect to the RLL (1, 7) modulation so as to demodulate theplayback signal. The read circuit 6 supplies, to the decoding processsection 7, the playback clock signal and a result of the demodulation ofthe playback signal.

The decoding process section 7 causes the second decoding processcircuit 71 b (i.e., a decoding process circuit for decoding the addressinformation recorded in the data region 102) to decode the addressinformation read out from the data region 102 (process S7) (secondaddress information decoding process step).

The process S7 makes it possible to obtain pieces of address informationwhich pieces constitute the respective address units “AU0” through“AU15” illustrated in (b) of FIG. 4. That is, the process S1 makes itpossible to obtain, as the pieces of address information, AUN0 throughAUN3, flag data, and Parity0 through Parity3, which are 9 symbolsconstituting an address unit (AU).

The ECC decoding section 8 carries out, as a process for correctingerrors in the address information, the ECC decoding with respect to eachof the pieces of the address information obtained from the decodingprocess section 7 (process S8) (second ECC decoding step). The processS8 makes it possible to obtain the address information whose errors arecorrected by the ECC decoding section 8

In accordance with the address information obtained from the ECCdecoding section 8, the control section 9 controls an operation of themotor 4 so that the motor 4 moves the optical pickup 3 to a givenposition in the data region 102. Then, the optical pickup 3 obtains dataof the optical disk 100 from a given address of the data region 102.That is, the optical pickup 3 plays back content recorded in the givenaddress of the data region 102 (process S9) (data region playing backstep).

A playback device plays back the optical disk 100 (i.e.,super-resolution medium) by carrying out the above processes S1 throughS9. Note that the processes S8 and S9 carried out with respect to thedata region 102 are identical to the respective processes S2 and S3carried out with respect to the medium information region 101.

Note that, in a case where an information recording medium to be playedback is not the optical disk 100 but a normal medium, such aninformation recording medium is subjected to the following processes S10through S13.

The control section 9 which determines that a type of an informationrecording medium loaded in the playback device 1 is not asuper-resolution medium (NO at S4) continuously uses the normal mediumplayback setting (i.e., a playback condition identical to the playbackcondition for playing back the medium information region) also as theplayback condition for playing back the data region.

Note that according to Embodiment 2, it is determined, also in a casewhere the medium information region is not played back, that a type ofan information recording medium to be played back is not asuper-resolution medium. Thus, in a case where (i) an informationrecording medium loaded in the playback device 1 is a normal medium and(ii) a medium information region of that information recording medium isimproperly played back due to adhesion of, for example, dirt, it isdetermined that the information recording medium is a normal medium.

As in the case of the process S6 (described earlier), the optical pickup3 accesses the data region (process S10) (data region accessing step).Subsequently, the decoding process section 7 decodes the addressinformation that has been read out from the data region by the firstdecoding process circuit 71 a (process S11) (first address informationdecoding process step).

Note that unlike the process S7 (described earlier), the process S11, inwhich an information recording medium loaded in the playback device 1 isa normal medium, makes it possible to decode, without using the seconddecoding process circuit 71 b, the address information read out from thedata region.

As in the case of the process S8 (described earlier), the ECC decodingsection 8 carries out, as the process for correcting errors in theaddress information, the ECC decoding with respect to each of the piecesof the address information obtained from the decoding process section 7(process S12) (second ECC decoding step).

Then, as in the case of the process S9 (described earlier), the opticalpickup 3 plays back the content recorded in a given address of the dataregion (process S13) (data region playing back step). The playbackdevice 1 thus plays back a normal medium by carrying out the aboveprocesses S1 through S4 and S10 through S13.

(Effect of Playback Device 1)

The playback device 1 includes the first decoding process circuit 71 afor decoding address information recorded in the medium informationregion 101. This allows the playback device 1 to play back information(particularly, medium identification information) on the optical disk100 from the medium information region 101 (a non-super-resolutionregion similar to that of a normal medium) of the optical disk 100(i.e., super-resolution medium).

This allows the playback device 1 to determine, by irradiating theinformation recording medium with playback light having normal mediumplayback power, whether an information recording medium to be playedback is a normal medium or a super-resolution medium. That is, aplayback device can use successful playback of the medium informationregion of the information recording medium as a criterion fordetermining that the optical disk 100 to be played back is asuper-resolution medium.

Further, even in a case where it is determined that an informationrecording medium to be played back is a normal medium, the playbackdevice 1, which includes the first decoding process circuit 71 a, canplay back address information and content each recorded in the dataregion of the normal medium.

The playback device 1 also includes the second decoding process circuit71 b for decoding address information recorded in the data region 102.Thus, in a case where it is determined that an information recordingmedium to be played back (e.g., the optical disk 100) is asuper-resolution medium, by irradiating the data region 102, in whichinformation is recorded with higher density than in the mediuminformation region 101, with playback light having super-resolutionplayback power, the address information and the content can be read outfrom the data region 102 without fail.

Thus, the playback device 1 can play back both the optical disk 100,which is a super-resolution medium, and a normal medium. That is, theplayback device 1 can play back the optical disk 100 while maintainingplayback compatibility with a normal medium. Further, the playbackdevice 1 can be said to be suitable to play back the optical disk 100,which is a super-resolution medium suitable to have a greater storagecapacity.

Assume here that a conventional playback device which can play back botha normal medium and a super-resolution medium (a conventionalsuper-resolution medium different from the optical disk 100, i.e., asuper-resolution medium which has a medium information region and a dataregion that are both super-resolution regions) cannot read out addressinformation recorded in the medium information region of an informationrecording medium. In this case, the conventional playback devicegenerally determines that an information recording medium loaded thereinis a super-resolution medium. Thus, it may be determined that forexample, a normal medium having a surface which is to be irradiated withplayback light and to which dirt has adhered is a super-resolutionmedium.

Meanwhile, only the playback device 1 that has allowed the firstdecoding process circuit 71 a to successfully carry out a decodingprocess with respect to address information irradiates a mediuminformation region of an information recording medium with playbacklight having normal medium playback power. Further, only the playbackdevice 1 that has allowed the second decoding process circuit 71 b tosuccessfully carry out the decoding process with respect to addressinformation irradiates the medium information region of the informationrecording medium with playback light having super-resolution mediumplayback power.

That is, in a case where the first decoding process circuit 71 a failsto carry out the decoding process with respect to address information,the information recording medium will not be irradiated with theplayback light having super-resolution medium playback power.

Furthermore, on the optical disk 100 which is used in the playbackdevice 1 as a super-resolution medium to be played back, the addressinformation of the medium information region 101 is recorded in thefirst address data format (described earlier). That is, the mediumidentification information recorded in the medium information region 101is read out by use of the playback light having normal medium playbackpower.

Thus, the playback device 1 in which the optical disk 100 is used as asuper-resolution medium to be played back can determine, withoutirradiating an information recording medium to be played back with theplayback light having super-resolution medium playback power, whetherthe information recording medium to be played back is a normal medium ora super-resolution medium.

In other words, it is impossible that the playback device 1 willdetermine, due to its inability to read out address information of amedium information region, that an information recording medium to beplayed back is a super-resolution medium. For example, though it isimpossible to read out address information of the medium informationregion of a normal medium having a surface which is to be irradiatedwith playback light and to which dirt has adhered, it will not bedetermined for such a reason that the information recording medium to beplayed back is a super-resolution medium.

Thus, according to the playback device 1, for example, in a case where amedium information region of an optical disk cannot be played back dueto, for example, presence of dirt, it is possible to prevent the opticaldisk from being erroneously recognized as a super-resolution medium.

This yields an effect of preventing a normal medium that essentially hasno problem from suffering from a situation in which the normal medium isbroken by being irradiated with playback light having higher playbackpower for playing back a super-resolution medium.

Embodiment 3

Embodiment 3 of the present invention will be described below withreference to FIGS. 10 and 11. Note that, for convenience, members havingfunctions identical to those of the respective members described inEmbodiments 1 and 2 are given respective identical reference numerals,and a description of those members is omitted in Embodiment 3.

(Configuration of Optical Disk 300)

The following description discusses, with reference to FIG. 10, aconfiguration of an optical disk 300 (information recording medium).FIG. 10 is a plan view showing an example of a configuration of theoptical disk 300. Note that as in the case of the optical disk 100 ofEmbodiment 1, Embodiment 3 discusses a case where the optical disk 300is a read-only Blu-ray (registered trademark) Disc (BD).

The optical disk 300, which is a discoid super-resolution medium, has(i) a medium information region 301 (first region), (ii) a data region302 (second region), and (iii) a blank region 303 (third region).

The medium information region 301 of Embodiment 3 is identical to themedium information region 101 of Embodiment 1. Further, the data region302 of Embodiment 3 is identical to the data region 102 of Embodiment 1.Thus, the optical disk 300 of Embodiment 3 is obtained by causing theoptical disk 100 of Embodiment 1 to further include the blank region303.

In the optical disk 300, the blank region 303 is provided so as to beouter than the medium information region 301 and inner than the dataregion 302. That is, the blank region 303 is provided between the mediuminformation region 301 and the data region 302 in a radial direction ofthe optical disk 300.

The blank region 303 is constituted by a pit group in which nosignificant information other than an address is recorded. That is, theblank region 303 is a region in which no significant information isrecorded. Further, the blank region 303 has a part in which an addressformat is changed (switched) from a first address data format to asecond data format.

The following description further specifically discusses the blankregion 303 with reference to FIG. 11. FIG. 11 is an enlarged view of aboundary part among the medium information region 301, the blank region303, and the data region 302 of the optical disk 300.

As illustrated in FIG. 11, the blank region 303 is provided between (a)the medium information region 301, in which address information isrecorded in the first address data format, and (b) the data region 302,in which address information is recorded in the second address dataformat. That is, the blank region 303 is provided so as to serve as aregion via which the medium information region 301 and the data region302 are connected.

As in the case of the medium information region 301, a region of theblank region 303 which region is closer to the medium information region301 (i.e., a region on an inner side of the blank region 303) isprovided with recesses and/or protrusions whose lengths are longer thanthat of an optical system resolution limit of a playback device andwhich are formed by a given modulation method (e.g., the 1-7 PPmodulation recording method) by a pit group that is suited to the firstaddress data format.

As in the case of the data region 302, a region of the blank region 303which region is closer to the data region 302 (i.e., a region on anouter side of the blank region 303) is provided with recesses and/orprotrusions whose lengths are shorter than that of an optical systemresolution limit of a playback device and which are formed by a givenmodulation method (e.g., the 1-7 PP modulation recording method) by apit group that is suited to the second address data format.

Note that it is not particularly limited where in the blank region 303the region of the blank region 303 which region is closer to the mediuminformation region 301 (i.e., a region in which the pit group that issuited to the first address data format is provided) and the region ofthe blank region 303 which region is closer to the data region 302(i.e., a region in which the pit group that is suited to the secondaddress data format is provided) are changed.

(Effect of Optical Disk 300)

It is demanded during playback of an information recording medium via aplayback device that playback of a data region (e.g., the data region302) in which content is recorded be started as soon as possible.

Content recorded in the optical disk 300 is played back via the playbackdevice by playing back medium identification information in the mediuminformation region 301 and then moving an optical pickup in a radialdirection while turning off tracking with respect to the mediuminformation region 301. Then, the playback device turns on tracking withrespect to the data region 302, and starts playing back the data region302.

In a case where playback of the data region is immediately started, theoptical pickup may track a position that is inner than an innermost partof the data region 302. That is, the optical pickup may track aninaccurate position.

Since the optical disk 300 of Embodiment 3 further includes the blankregion 303, as in the case of the data region 302, a region inner than astart region of the data region 302 (i.e., the innermost part of thedata region 302) is also provided with recesses and/or protrusions whichinclude a recess and/or a protrusion whose length is shorter than thatof an optical system resolution limit of a playback device and which areformed by a given modulation method by a pit group that is suited to thesecond address data format.

Thus, even in a case where the optical pickup tracks an inaccurateposition, a region outer than the blank region 303 will be played back.This allows the playback device to check a playback position by use of aplayback setting for playing back the data region 302.

Therefore, the playback device can move the optical pickup to a givenposition in the data region 302 with reference to the playback positionthat has been checked as a result of playback of the region outer thanthe blank region 303.

That is, the optical disk 300 of Embodiment 3 yields an effect ofallowing a playback device to immediately start playing back contentwith higher reliability.

Embodiment 4

Embodiment 4 of the present invention will be described below withreference to FIGS. 12 and 13. Note that, for convenience, members havingfunctions identical to those of the respective members described inEmbodiments 1 through 3 are given respective identical referencenumerals, and a description of those members is omitted in Embodiment 4.

(Configuration of Optical Disk 300)

The following description discusses, with reference to FIG. 12, aconfiguration of an optical disk 400 (information recording medium).FIG. 12 is a plan view showing an example of a configuration of theoptical disk 400. Note that as in the case of the optical disk 100 ofEmbodiment 1, Embodiment 4 discusses a case where the optical disk 400is a read-only Blu-ray (registered trademark) Disc (BD).

The optical disk 400, which is a discoid super-resolution medium, has(i) a medium information region 401 (first region) and (ii) a dataregion 402 (second region). The optical disk 400 differs from each ofthe optical disk 100 of Embodiment 1 and the optical disk 300 ofEmbodiment 3 in that the data region 402 has a track pitch shorter thanthat of the medium information region 401. The other configurations andrecorded information of the optical disk 400 are identical to those ofthe optical disk 100 of Embodiment 1.

FIG. 13 is an enlarged view of a boundary part between the mediuminformation region 401 and the data region 402 of the optical disk 400.As illustrated in FIG. 13, the medium information region 401 is providedwith a plurality of tracks T1 each constituted by pits P1, and the dataregion 402 is provided with a plurality of tracks T2 each constituted bypits P2.

The medium information region 401 has a track pitch which is indicatedby a track pitch TP1 that is a distance between two adjacent tracks T1in a radial direction. The data region 402 has a track pitch which isindicated by a track pitch TP2 that is a distance between two adjacenttracks T2 in the radial direction.

The tracks T1 and T2 are provided so that the track pitch TP1 is longerthan the track pitch TP2. That is, the data region 402 has the trackpitch TP2 which is shorter than the track pitch TP1 of the mediuminformation region 401.

For example, according to Embodiment 4, the tracks T1 and T2 areprovided so that the track pitch TP1 (i.e., a track pitch identical tothat of the optical disk 100) has a length of 0.35 μm and the trackpitch TP2 has a length of 0.29 μm.

It is natural that these values be optionally changeable in a case wherethe track pitch TP1 is greater than the track pitch TP2. Further, thetrack pitch TP1 does not necessarily need to be identical to a trackpitch of the optical disk 100.

A functional layer (not illustrated, corresponding to the functionallayer 192 illustrated in FIG. 3) of the optical disk 400 only needs tobe a film (i) that allows a playback optical system to read informationrecorded by a prepit group provided on a surface of a substrate (notillustrated, corresponding to the substrate 193 illustrated in FIG. 3)of the optical disk 400, and (ii) that allows the track pitch TP2 tohave a length (e.g., 0.29 μm) shorter than that of the track pitch TP1.

Specifically, as in the case of the functional layer 192 of the opticaldisk 100, the functional layer of the optical disk 400 can be made of,for example, a stack of (i) a light absorption film having a thicknessof 8 nm and made of a material such as Ta, Al, Ag, Au, or Pt, or amixture of these materials and (ii) a super-resolution playback filmmade of a material such as ZnO, CeO₂, or TiO₂.

(Effect of Optical Disk 400)

According to the optical disk 400, in order that the data region 402 hasthe track pitch TP2 which is shorter than the track pitch TP1 of themedium information region 401, the tracks T1 are provided in the mediuminformation region 401, and the tracks T2 are provided in the dataregion 402.

Thus, for example, the optical disk 400, which allows a further increasein number of tracks in the data region 402 as compared with, forexample, the case of the optical disk 100, yields an effect of having agreater storage capacity. That is, the optical disk 400 allows recordedinformation to be denser.

The playback device 1 which plays back information recorded in theoptical disk 400 has a function of being suited to both the track pitchTP1 and the track pitch TP2 (i.e., a function of being suited not onlyto the track pitch TP1 but also to the track pitch TP2) so as to controltracking with respect to the medium information region 401 and the dataregion 402 without fail.

This function can be carried out by, for example, obtaining a value ofthe track pitch TP2 as information on the optical disk 400 when theoptical pickup 3 obtains medium identification information from themedium information region 401, and reflecting the obtained value in anoperation that the optical pickup 3 carries out so as to read outinformation recorded in the data region 402.

Embodiment 5

Embodiment 5 of the present invention will be described below withreference to FIG. 14. Note that, for convenience, members havingfunctions identical to those of the respective members described inEmbodiments 1 through 4 are given respective identical referencenumerals, and a description of those members is omitted in Embodiment 5.

(Configuration of Optical Disk 500)

The following description discusses, with reference to FIG. 14, aconfiguration of an optical disk 500 (information recording medium).FIG. 14 is a plan view showing an example of a configuration of theoptical disk 500. Note that as in the case of the optical disk 100 ofEmbodiment 1, Embodiment 5 discusses a case where the optical disk 500is a read-only Blu-ray (registered trademark) Disc (BD).

The optical disk 500, which is a discoid super-resolution medium, has(i) a medium information region 501 (first region), (ii) a data region502 (second region), and (iii) a blank region 503 (third region).

The medium information region 501 and the data region 502 of Embodiment5 are identical to the medium information region 401 and the data region402, respectively, of Embodiment 4. That is, the data region 502 has atrack pitch TP2 (of, for example, 0.29 μm) which is shorter than a trackpitch TP1 (of, for example, 0.32 μm) of the medium information region501. Thus, the optical disk 500 of Embodiment 5 is obtained by causingthe optical disk 400 of Embodiment 4 to further include the blank region503.

As in the case of the blank region 303 of Embodiment 3, the blank region503 of Embodiment 5 is a region that is provided between the mediuminformation region 501 and the data region 502 in a radial direction ofthe optical disk 500. The blank region 503 is a region in which nosignificant information other than an address is recorded.

The blank region 503 has a part in which an address format is changedfrom a first address data format to a second address data format.Further, the blank region 503 has a track pitch TP3 that is provided soas to be shorter from the medium information region 501, which is innerthan the blank region 503, toward the data region 502, which is outerthan the blank region 503.

That is, the data region 503 has the track pitch TP3 which is arrangedso that (i) the blank region 503 has an innermost part (a boundarybetween the blank region 503 and the medium information region 501)where TP3=TP1=0.32 μm, and (ii) the blank region 503 has an outermostpart (i.e., a boundary between the blank region 503 and the data region502) where TP3=TP2=0.29 μm.

Thus, the blank region 503 is provided so as to have the track pitch TP3which changes from the track pitch TP1 of the medium information region501 to the track pitch TP2 of the data region 502. Note that how thetrack pitch TP3 of the blank region 503 changes is not particularlylimited.

Note that the track pitch TP3 does not necessarily need to be shorterfrom the inner side toward the outer side of the optical disk 500. Forexample, in a case where the data region 502 is provided on an innermostside of the optical disk 500, and the medium information region 501 isprovided on an outermost side of the optical disk 500, the track pitchTP3 only needs to be shorter from the outer side toward the inner sideof the optical disk 500.

(Effect of Optical Disk 500)

Since the optical disk 500 of Embodiment 5 further includes the blankregion 503, as in the case of the data region 502, a region inner than astart region of the data region 502 (i.e., the innermost part of thedata region 502) is also provided with recesses and/or protrusions whichinclude a recess and/or a protrusion whose length is shorter than thatof an optical system resolution limit of a playback device and which areformed by a given modulation method (e.g., the 1-7 PP modulationrecording method) by a pit group that is suited to the second addressdata format.

Thus, as in the case of Embodiment 3, even in a case where the opticalpickup tracks an inaccurate position, a region outer than the blankregion 503 will be played back. This allows the playback device to checka playback position by use of a playback setting for playing back thedata region 502.

Therefore, the playback device can move the optical pickup to a givenposition in the data region 502 with reference to the playback positionthat has been checked as a result of playback of the region outer thanthe blank region 503.

That is, as in the case of the optical disk 300 of Embodiment 3, theoptical disk 500 of Embodiment 5 yields an effect of allowing a playbackdevice to immediately start playing back content with higherreliability.

Furthermore, as in the case of the optical disk 400 of Embodiment 4,according to the optical disk 500 of Embodiment 5, the data region 502has the track pitch TP2 which is shorter than the track pitch TP1 of themedium information region 501.

Thus, as in the case of the optical disk 400 of Embodiment 4, theoptical disk 500 of Embodiment 5 allows an increase in number of tracksin the data region 502. This yields an effect of allowing the opticaldisk 500 to have a greater recording capacity. That is, the optical disk500 allows recorded information to be denser.

Modified Example

The above description has discussed Embodiments 1 through 5 by taking,as examples, cases where the optical disks 100, 300, 400, and 500, eachof which is an information recording medium, are each assumed to be aBD. However, the information recording medium is not limited to a BD butcan be exemplified by various optical disks such as other optical readdisks, magneto-optical disks, and phase change disks. Alternatively, theinformation recording medium can be a magnetic disk.

Note that the above description of Embodiment 2 has taken, as anexample, particularly a case where the playback device 1 plays back theoptical disk 100. Note, however, that the playback device 1 can playback the optical disks 300, 400, and 500 as well as the optical disk100.

Furthermore, the above description has discussed Embodiments 1 through 5by taking, as examples, only cases where the optical disks 100, 300,400, and 500 are played back as information recording mediums, but suchoptical disks are not limited to read-only information recordingmediums. The optical disk 100, 300, 400, and 500 can also be recordableinformation recording mediums or rewritable information recordingmediums.

[Software Implementation Example]

Control blocks (especially the control section 9) of the playback device1 can be realized by a logic circuit (hardware) provided in anintegrated circuit (IC chip) or the like or can be alternativelyrealized by software as executed by a CPU (Central Processing Unit).

In the latter case, the playback device 1 includes a CPU that executesinstructions of a program that is software realizing the foregoingfunctions; ROM (Read Only Memory) or a storage device (each referred toas “storage medium”) in which the program and various kinds of data arestored so as to be readable by a computer (or a CPU); and RAM (RandomAccess Memory) in which the program is loaded. An object of the presentinvention can be achieved by a computer (or a CPU) reading and executingthe program stored in the storage medium. Examples of the storage mediumencompass “a non-transitory tangible medium” such as a tape, a disk, acard, a semiconductor memory, and a programmable logic circuit. Theprogram can be supplied to the computer via any transmission medium(such as a communication network or a broadcast wave) which allows theprogram to be transmitted. Note that the present invention can also beachieved in the form of a computer data signal in which the program isembodied via electronic transmission and which is embedded in a carrierwave.

Summary

An information recording medium (optical disk 100) according to Aspect 1of the present invention includes: a first region (medium informationregion 101) in which type identification information (mediumidentification information) for identifying a type of the informationrecording medium is recorded by recesses and/or protrusions which areformed by a given modulation method and whose lengths are longer than alength of an optical system resolution limit of a playback device; and asecond region (data region 102) in which content data is recorded byrecesses and/or protrusions which are formed by the given modulationmethod and which include a recess and/or a protrusion whose length isshorter than the length of the optical system resolution limit, thefirst region containing first address information recorded therein in afirst address data format, and the second region containing secondaddress information recorded therein in a second address data formatthat differs from the first address data format.

According to the arrangement, in the second region of the informationrecording medium according of an aspect of the present invention,content data is recorded by recesses and/or protrusions which include arecess and/or a protrusion whose length is shorter than the length ofthe optical system resolution limit. Thus, the information recordingmedium is a super-resolution medium.

Furthermore, the information recording medium according to an aspect ofthe present invention is arranged such that the address information ofthe first region in which type identification information is recorded isrecorded in the first address data format. The address information ofthe second region in which content data is recorded is recorded in thesecond address data format that differs from the first address dataformat.

Here, the first address data format has a data structure identical to,for example, a data structure of a normal medium as shown in (a) of FIG.4. The second address data format has a data structure for asuper-resolution medium which data structure enables recording of denserdata than a normal medium (e.g., a data structure in which clusteraddresses are greater in number of bits (number of addresses) than thoseof a normal medium), which data structure is for example as shown in (b)of FIG. 4.

Meanwhile, a conventional super-resolution medium which differs from theinformation recording medium according to an aspect of the presentinvention is arranged such that the data structure for asuper-resolution medium which data structure enables recording of denserdata than a normal medium is applied to not only a second region, inwhich content data is recorded, but also a first region, in which typeidentification information is recorded. For example, according to aconventional super-resolution medium, a data structure for asuper-resolution medium as shown in (b) of FIG. 15 is applied to thefirst region.

Thus, according to a playback device having downward playbackcompatibility and capable of playing back a conventionalsuper-resolution medium, an inability to play back the mediuminformation region is a criterion for determining that the informationrecording medium is a super-resolution medium. Thus, in a case where afirst region of an information recording medium, which is a normalmedium, cannot be played back due to some reason such as adhesion ofdirt to the information recording medium, it may be determined that theinformation recording medium is a super-resolution medium.

However, the information recording medium according to an aspect of thepresent invention allows a playback device to use successful playback ofthe first region as a criterion for determining that the informationrecording medium to be played back is a super-resolution medium. Thus,in a case where the first region cannot be played back due to somereason such as adhesion of dirt to the information recording medium, itis determined that the information recording medium is a normal medium.

That is, the information recording medium according to an aspect of thepresent invention can prevent a playback device from losing its downloadcompatibility. This can prevent the playback device from erroneouslydetermining that a normal medium is a super-resolution medium.

Thus, it is possible to prevent the occurrence of a situation in which anormal medium that is irradiated with playback light having greaterplayback power for playing back a super-resolution medium is broken.This yields an effect of allowing the playback device to play back theinformation recording medium with higher reliability.

A playback device (1) according to Aspect 2 of the present invention forplaying back an information recording medium of Aspect 1 can include: afirst address information decoding process section (first decodingprocess circuit 71 a) for decoding the first address informationrecorded in the first region; and a second address information decodingprocess section (second decoding process circuit 71 b) for decoding thesecond address information recorded in the second region.

According to the arrangement, the playback device which includes thefirst address information decoding process section can decode addressinformation recorded in the first address data format in the firstregion (i.e., a region in which type identification information isrecorded). Similarly, the playback device which includes the secondaddress information decoding process section can decode addressinformation recorded in the second address data format in the secondregion (i.e., a region in which content data is recorded).

Thus, it is possible to provide a playback device which is suitable toplay back the information recording medium according to an aspect of thepresent invention while having playback compatibility with a normalmedium.

In Aspect 3 of the present invention, the information recording medium(optical disk 300) can be arranged to further include, in Aspect 1, athird region (blank region 303) which is provided between the firstregion and the second region and in which no significant informationother than an address is recorded, the third region having (i) a regionthat is closer to the first region and is provided with recesses and/orprotrusions whose lengths are longer than the length of the opticalsystem resolution limit and which are formed by a given modulationmethod and (ii) a region that is closer to the second region and isprovided with recesses and/or protrusions whose lengths are shorter thanthe length of the optical system resolution limit and which are formedby the given modulation method.

According to the arrangement, as in the case of the second region, aregion of the third region which region is closer to the first regionthan to a start region of the second region is also provided withrecesses and/or protrusions which include a recess and/or a protrusionwhose length is shorter than the length of an optical system resolutionlimit of a playback device and which are formed by the given modulationmethod.

Thus, even in a case where the optical pickup which has played back thefirst region and then moved from the first region to the second regionso as to start playing back the second region tracks an inaccurateposition, a region of the third region which region is closer to thesecond region will be played back.

Thus, the playback device can move, by use of a playback setting forplaying back the second region, the optical pickup to a given positionin the second region with reference to a playback position that has beenchecked as a result of playback of the third region. This yields aneffect of allowing a playback device to play back content with higherreliability.

In Aspect 4 of the present invention, the information recording medium(optical disk 400) can be arranged such that, in Aspect 1 or 3, thesecond region has a track pitch (TP2) that is shorter than a track pitch(TP1) of the first region.

The arrangement allows a further increase in number of tracks in thesecond region as compared with the case where the track pitch of thesecond region is equal to the track pitch of the first region. Thisallows the information recording medium to store denser data.

In Aspect 5 of the present invention, the information recording medium(optical disk 500) can be arranged such that, in Aspect 3, (i) thesecond region has the track pitch that is shorter than the track pitchof the first region, and (ii) the third region has a track pitch (TP3)that is shorter from the first region toward the second region so that(a) the third region is equal in track pitch to the first region at aboundary between the first region and the third region and (b) the thirdregion is equal in track pitch to the second region at a boundarybetween the second region and the third region.

The arrangement allows a further increase in number of tracks in thesecond region of the information recording medium which further includesthe third region. This allows the information recording medium to storedenser data.

A playback method according to Aspect 6 of the present invention forcontrolling the playback device according to Aspect 2 can include (i) afirst address information decoding process step of decoding addressinformation recorded in the first region, and (ii) a second addressinformation decoding process step of decoding address informationrecorded in the second region.

The arrangement allows the playback device to suitably play back theinformation recording medium according to an aspect of the presentinvention as in the case of Aspect 2.

The playback device according to Aspect 2 may be realized by a computer.In this case, the present invention encompasses: a control program forthe playback device which program causes a computer to operate as theforegoing sections of the playback device so that the playback devicecan be realized by the computer; and a computer-readable storage mediumstoring the control program therein.

Supplementary Note

The present invention is not limited to the embodiments, but can bealtered by a skilled person in the art within the scope of the claims.An embodiment derived from a proper combination of technical means eachdisclosed in a different embodiment is also encompassed in the technicalscope of the present invention. Further, it is possible to form a newtechnical feature by combining the technical means disclosed in therespective embodiments.

Note that the present invention can also be expressed as below.

An information recording medium according to an aspect of the presentinvention includes: a first region in which type identificationinformation for identifying a type of the information recording mediumis recorded by recesses and/or protrusions which are formed by a givenmodulation method and whose lengths are longer than a length of anoptical system resolution limit of a playback device; and a secondregion in which content data is recorded by recesses and/or protrusionswhich are formed by the given modulation method and which include arecess and/or a protrusion whose length is shorter than the length ofthe optical system resolution limit, the first region containing firstaddress information recorded therein in a first address data format, andthe second region containing second address information recorded thereinin a second address data format that differs from the first address dataformat.

A playback device according to an aspect of the present invention forplaying back an information recording medium according to an aspect ofthe present invention, includes: a first address information decodingprocess section for decoding the first address information recorded inthe first region; and a second address information decoding processsection for decoding the second address information recorded in thesecond region.

INDUSTRIAL APPLICABILITY

The present invention is applicable to (i) an information recordingmedium in which information can be recorded and (ii) a playback devicecapable of playing back the information recording medium.

REFERENCE SIGNS LIST

-   -   1 Playback device    -   71 a First decoding process circuit (first address information        decoding process section)    -   71 b Second decoding process circuit (second address information        decoding process section)    -   100, 300, 400 and 500 Optical disk (information recording        medium)    -   101, 301, 401 and 501 Medium information region (first region)    -   102, 302, 402 and 502 Data region (second region)

The invention claimed is:
 1. An information recording medium comprising:a first region in which type identification information for identifyinga type of the information recording medium is recorded by recessesand/or protrusions which are formed by a given modulation method andwhose lengths are longer than a length of an optical system resolutionlimit of a playback device; and a second region in which content data isrecorded by recesses and/or protrusions which are formed by the givenmodulation method and which include a recess and/or a protrusion whoselength is shorter than the length of the optical system resolutionlimit, wherein the first region containing first address informationrecorded therein in a first address data format, the second regioncontaining second address information recorded therein in a secondaddress data format that differs from the first address data format, andthe second address data format includes cluster addresses with a greaternumber of bits than a number of bits included in cluster addresses inthe first address data format.
 2. A playback device for playing back aninformation recording medium recited in claim 1, said playback devicecomprising: a first address information decoding process section thatdecodes the first address information recorded in the first region; anda second address information decoding process section that decodes thesecond address information recorded in the second region.